In Common Blockchain Design, What Is One Common Method to "Chain

Multiple Choice

In common blockchain design, what is one common method to "chain" blocks of data together in order?

A) Store the hash of the previous block within the current block
B) Having the genesis node store an ordered, mutable array of block hashes
C) Writing each block into a separate file on the hard disk of the node
D) Assigning an order number to each block so they can be sorted when requested